Cables for actuating a brake device and a gearbox by being inserted into tubes constituting a bicycle frame so as to prevent corrosion of the cables and improve the aesthetic appearance of the bicycle (are known (e.g.) U.S. Pat. No. 4,585,246).
FIG. 5 depicts a conventional structure for threading a cable through the bicycle frame. In FIG. 5, a lug 1a of a head tube 1 is fitted into an end of a top tube 2 and a lug 3a of a seat bracket 3 is also fitted into the other end of the top tube 2. The lug 1a is formed with a cable outlet 4 and the lug 3a is formed with a cable inlet 5.
A cable 6 for a brake device is pushed into the top tube 2 through the cable inlet 5 and the leading tip 6a of the cable 6 is then pushed out from the cable outlet 4 with the cable 6 threaded in the top tube 2.
The cable inlet 5 and the cable outlet 4 may be formed in the top tube 2.
In order to push out the leading tip 6a of the cable 6 from the cable outlet 4, it is necessary to form a through hole 7 in the head tube 1 to communicate the head tube 1 with the top tube 2. Thus, a finger is inserted into the head tube 1 to guide the leading tip 6a of the cable 6 toward the cable outlet 4 with the tip of the finger while the cable 6 is pushed so that the leading tip 6a of the cable 6 is pushed out from the outlet 4.
However, when the leading tip 6a of the cable 6 is guided with the finger tip as described above, it is difficult to move the finger in the head tube 1 and the top tube 2 freely due to smallness of the through hole 7. Accordingly, considerable labor and time are required to thread the cable 6 through the top tube 2.
Further, as depicted in FIG. 6, a spoke 8 (or a small-diameter rod) of the bicycle is inserted into the cable outlet 4 and the leading tip of the spoke 8 is fitted into the leading tip of the cable 6. Thus, the leading tip of the cable 6 is pushed out from the cable outlet 4 while being guided toward the cable outlet 4 with the spoke 8. Such an operation of threading the cable is suitable when the finger cannot be inserted into the head tube 1 or the finger cannot reach the leading tip 6a of the cable 6. However, it is very difficult to insert the spoke 8 into the leading tip 6a of the cable 6 since the leading tip 6a of the cable 6 moves, and hence considerable labor and time are required.